There are definitely 2 distinct cultures of developers using the MS Web Stack. Webforms (what most people typically think of when they thing of .NET) is an attempt to get desktop developers on the web. While it's possible to get good markup out of Webforms, most of the default features are a table-based, inline styled abomination. Until MVC came out, I actually worked on an open source project that focused on fixing the markup generated by ASP.NET.

That being said, the new generation of ASP.NET MVC devs is top notch. People like Scott Hanselman and Phill Haack have helped make some vast improvements in the stack.